Plastics are widely used in both durable and non-durable applications. The majority of non-durable plastics are used in initial packaging of goods and food service packaging, often in single use applications.
The disposal of plastic products results in huge amounts of waste. Recyclable plastic products must be cleaned before recycling, which consumes additional energy. Due to incomplete cleaning and degradation of the polymers during processing they are often unable to be recycled into similar quality goods.
Foam plastic products produced through conventional means utilizing a chemical blowing agent solve some of the problems of solid plastic products by adding insulation and cushioning to their benefits, but often create new problems. Foamed plastic may become friable, and form small pellets nearly impossible to separate from a waste stream. The surface of foamed plastics is often cellular and unattractive to consumers.
The chemical blowing agents, fluorocarbons and chlorofluorocarbons, used in producing many foams have negative environmental effects, and the contamination of plastics from these blowing agents may render them non-recyclable.
Solid state foaming utilizing carbon dioxide, or other high pressure gas, as a foaming agent has been explored as a resolution to some of the above problems. Semi-continuous foaming is a method of interleaving a saturated roll of polymer with a gas-channeling means, which allows saturation of polymers prior to thermoforming. Semi-continuous production is a labor intensive process which consumes an interleaving layer and requires a large amount of plastic. Plastic loses gas during processing, and a large roll of plastic may take a long time to process, so the properties at the start of a foam roll may differ from those of the end of a roll.
The problems concerning the utilization of plastics in packaging, in both foam and solid form, extend to durable goods as well. A particular area of plastic usage for durable goods is composites, in which multiple phase separated materials are bonded together to create a single part with better properties. The center section of these parts are often foam. Most foams produced for these applications cannot be recycled after bonding, and are not biodegradable.